SOURCE

//单利
// class Single {
//   constructor(name) {
//     this.name = name;
//   }
//   static getInstance(name) {
//     // 静态方法
//     if (!this.instance) {
//       // 关键代码 this指向的是Single这个构造函数
//       this.instance = new Single(name);
//     }
//     return this.instance;
//   }
// }

// let single1 = Single.getInstance("name1");
// let single2 = Single.getInstance("name2");
// console.log(single1.name,single2.name);  // true

class Combine {
    constructor() {
        this.list = [];
    }
    add(fn) {
        console.log('add',fn)
        this.list.push(fn);
        return this; // 链式调用
    }
    excute() {
        for (let i = 0; i < this.list.length; i++) {
            console.log(this.list[i])
            if(this.list[i].excute1){
                this.list[i].excute1();
            }else{
                this.list[i].excute()
            }

        }
    }
}
let comb1 = new Combine();
comb1
    .add({
        excute1() {
            console.log(1);
        }
    })
    .add({
        excute1() {
            console.log(2);
        }
    });

let comb2 = new Combine();
comb2
    .add({
        excute1() {
            console.log(3);
        }
    })
    .add({
        excute1() {
            console.log(4);
        }
    });

let comb3 = new Combine();
comb3
    .add({
        excute1() {
            console.log(5);
        }
    })
    .add({
        excute1() {
            console.log(6);
        }
    });
comb2.add(comb3);

let comb4 = new Combine();
comb4.add(comb2).add(comb1);
comb4.excute();